Cutters for electric shavers



Aug. 25, 1959 KOHNER ETAL 2,900,719

CUTTERS FOR ELECTRIC SHAVERS I Filed Aug. 24, 1956 2 Sheets-Sheet l FIGI INVENTORS: M ELVIN KOHNER JAMES A. WRl G Aug. 25, 1959 KOHNER ET AL 2,900,719

, CUTTERS FOR ELECTRIC SHAVERS F iled Aug. 24, 1956 2 Sheets-Shem 2 1] 1H. 21 lulu-1 Hm W INVENTORS: MELVIN KOHNER JAMES .WRIGH United States Patent CUTTERS FOR ELECTRIC SHAVERS Melvin Kohner, Racine, Wis, and James A. -Wright, Chicago, 111., assignors to Supreme Products Corporation, Chicago, 111., a corporation of Illinois Application August 24, 1956, Serial No. 606,133

2 Claims. (CI. 30-43) This invention relates to cutters for electric shavers. More particularly it has to do with an electric shaver cutter of the type which moves relative to and cooperates with a perforated comb in order to sever whiskers protruding through the perforations in the comb.

The general object of the present invention is to provide a new and improved electric shaver cutter.

Another object of the present invention is to provide an electric shaver cutter which is simple and easy to manufacture including a structural shape which withstands strains and will not warp or bend when heat treated, and which when employed in cooperation with a perforated comb is easily cleaned, and extremely efiicient, and which is durable and long-lasting.

Still another object of the present invention is to provide an improved self-sharpening electric shaver cutter;

A still further object is to provide an electric shaver cutter of the foregoing character which is light-weight and thus requires a. minimum of motive power.

It is another object of the present invention to provide a new and improved method of manufacturing an electric shaver cutter.

A related object is to provide a method of manufacturing electric shaver cutters capable of achieving each and every one of the above mentioned objects.

It is also an aim of the present invention to provide such a method which is readily adapted to standard manufacturing techniques and equipment and includes the processing of two semi-cylindrical members simultaneously to provide a balanced work piece load for machining operations including automatic screw machines.

These and other objects of the invention are achieved by forming on a body member a plurality of semi-circular parallel cutter-blades projecting from and spaced along the length of the body member; each of these cutter-blades comprises a soft middle metal layer bounded by a pair of hard metal layers. The end-surfaces of the cutter-blades which in use cooperate with and are spring-urged against the flexible comb of the shaver thus each comprise a region of soft metal bounded by a pair of strips of harder metal. The hard metal portions of the cutter-blade end surfaces are the active cutting elements; the intermediate soft metal layers serve to mechanically sup-port the preferably relatively narrow hard metal cutting edges. Also, the softer metal intermediate portions wear away below the cutting edges by virtue of the abrasive effects of the cut whiskers, leaving only the hard metal cutting edges in physical contact with the comb and thereby reducing friction and resultant heat; such wearing awayof the intermediate soft metal layers effects a hollowing of the cutter-blade end surfaces.

In. accordance with another aspect of the invention, such a cutter is manufactured from a bar of soft metal extensions by first forming the plurality of parallel blades placed along the length of the bar and then surfacehardening the blades, as by a conventional fast-quenching or quick-carbonization step, to form a very hard layer.

or skin on the blades, The'cuter. end-smfacesof the 2,900,719 I Patented Aug. 25, 1959 blades are then subjected to a grinding or similar operation to remove the hardened outer edge-surface of the blades each to expose the soft metal portion thereof whereby there is formed the above mentioned soft metal intermediate surfaces each bounded by a pair of hard metal strips which, when the cutter is placed in use, senv as extremely effective cutting edges.

The features of the invention which are believed to be novel are set forth with particularity in the appended claims. The organization and manner of operation of the invention, together with further objects and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying drawings in which:

Fig. 1 is a view, partially broken away, of an electric shaver embodying the cutter of the present invention;

Fig. 2 is a fragmentary cross-sectional view taken along the line "22 in Fig. 1;

Fig. 3 is a fragmentary perspective view of suitable bar stock from which the cutter of the present invention may be formed;

Fig. 4 is a view taken from one side of a cutter form from the bar stock of Fig. 3;

Fig. 5 is a bottom view of the cutter of Fig. 4;

Fig. 6 is a perspective view of a pair of the cutters, formed and machined, in position to be mounted on a rotatable spindle;

Fig. 7 is an enlarged fragmentary sectional view showing one of the cutters of Fig. 6 disposed against a grinding surface; and

'Fig. 8 is a partial plan view of the comb showing the; cutting edge construction.

"In the embodiment shown in Figs. 1 and 2 for pur poses of illustration, an electric shaver '10 is shown embodying the preferred form of the invention which-includes the cutter 12 construction and its cooperation with the comb 2t). Shaver 10 includes a housing 14 of a plastic or other suitable material to which a comb-carrier 1 5 is detachably mounted. The comb-carrier 15 is remov-- able upon the depression of a spring-latch button'1-6h Shaver 10 also includes a start-stop switch button 17 and suitabel electrical terminals 18. l

More particularly with respect to the upper portion of shaver 10, the comb-carrier 15 supports a perforated metal comb 20 which is a normally flat member which curves smoothly around and over the top of shaver 10 as secured at its ends by rivets 21 to the back and front side portions of comb-carrier 15.

In the embodiment shown (Fig. 8) the apertures 20a and 2% in the comb are preferably arranged to have the rows of cutter openings slightly inclined with respect to the edges of the cutter and'in each row a small opening Ztla is alternated with an elongated opening 20b and so staggered as shown in the drawing as between rows that a small opening is located opposite along opening. The long openings have projections 200 from their sides to. prevent hair therein from sliding under the action of the cutters.

The cutter 12 is disposed immediately beneath the curved surface of comb 20 and comprises a body mem ber 13 from which a plurality of parallel cutter-blades 22 project outwardly toward the comb. The blades 22 are spaced along the length of body member 13 and have, an external contour preferably semi-cylindrical which under spring pressure shapes the cutter 12 so that the blades mate with the under surface of comb 20 with a light cutting pressure when the cutter is pressed upward ly thereagainst. Q

Cutter 1.2 is reciprocated endwise to move the cutting surfaces 23 of the cutter across the perforations in comb 20, by the action of a motor (not shown) enclosed within the housing 14. ,Such,reciprocationvmeansiswelli known in the prior art and therefore is not described in detail here. Suflice it to say for the present that the motor effects sidewise rocking back and forth to the right and left as viewed in Fig. 1 of an upwardly projecting post 25 upon the end of which cutter 12 is mounted. Cutter 12is placed over the free end of post 25, the latter protruding upwardly through a hole 26 in the bottom ofa channel 27 cut lengthwise into the bottom of cutter 12. A washer 28 collared on post 25 is shaped to fit snugly into channel 27 and is secured to cutter 12 by a screw 29 locked in place by means of glyptal cement. A spring 30 seated in an eyelet 31 afiixed around the bottom of post 25 presses against the under side of washer ZSthereby urging cutter 12 and more particularly end-surfaces 23 into mating engagement with comb 29. A snap-ring 32 locked on the end of post' 25 prevents dislodgement of cutter 12 from the post upon removal of comb-carrier 15 for cleaning purposes.

In use, cutter 12 is thus reciprocated back and forth so that whiskers protruding through the perforations in comb 20 are severed by the action of cutter-blades 22 moving across the perforations. Preferably, these perforations comprise parallel columns of alternate long holes staggered in each column with respect to the next so that they overlap with respect to their cooperation with the cutters. It is also preferred to align the columns of holes obliquely around the curved portion of the comb, as shown.

Turning now more directly to the cutter of the present invention, the best understanding thereof is obtainable by observing the unique method of manufacturing the same. While cutter 12 may be of various shapes and contours, it is apparent that the final outer contour of blades 22 is selected in accordance with the corresponding contour desired in the comb with which it cooperates. Preferably, the external contours of the cutter-blades herein described are curved to provide the semi-cylindrical contour shown.

The invention contemplates forming cutter 12 from soft metal extruded tube stock. Fig. 3 illustrates such a metal tube 35 of semi-cylindrical cross-section. Further-v more, for the purpose of greatly facilitating manufacturing and equally for the purpose of producing a cutter of light Weight so as to require a minimum of driving power when in use, bar 35, the walls, though of substantially uniform thickness are only thick enough to provide a thin bottom wall or web 35a between the bottoms of the cutters and a fiat wall 42 interconnecting the edges of the cylindrical portion. Such a semi-annular tube is readily formed by conventional and Well-known extrusion processes wherein the metal stock is forced through a die of corresponding shape. Alternatively, bar 35 may be formed by a rolling process or by other well-known methods capable of producing a bar or semi-annular crosssection and thus having a hollow interior 36.

When automatic screw machines are used, the blades 22 are shaped by forming a plurality of parallel grooves 40 in and spaced along the length of the outer curved portion 41 of bar 35. In doing this in accordance with one aspect of the invention, a pair of the bars 35 are placed back-to-back, with their fiat bottom surfaces 42 face-to-face to be fed through the chuck of the machine as mounted for rotation relative to a plurality of suitable cutting tools advanced radially to form grooves 40. In order to support the two bars in perfect position against deflection and the feed pressure of the cutters, the free end portions projecting beyond the chuck are received over the forked ends of a live spindle 45 with the ends thereof received snugly in the tubes to follow their inside shape as more particularly described hereafter in connec- 4 cutting tools, mounted on a suitably traversed head are then moved into engagement with the rotating bars whereupon grooves 40 are turned into the bars leaving the correspondingly spaced plurality of blades 22. A cut-off tool then severs the cuttters from the tube stock, the live spindle is retracted and the two pieces drop into a basket.

Thereafter, the two severed grooved portions are machined to form channel 27 lengthwise of bottom flat sur-,.

mitting normal machining operations. Thus, bar 35 is' of a degree of hardness such that ordinary lathe tools may be utilized in forming grooves 40 and in severing the grooved lengths of the bars from the remainders thereof.

The invention contemplates hardening only discrete portions of cutter-blades 22 to form a cutting surface of lasting durability and efiiciency. In accordance with the inventive method the'grooved, severed portion of bar 35, or at least the grooved outer curved portion thereof, is surface-hardened. Such surface-hardening is readily achieved by contentional so-called fast-quenching techniques well-known in the metallurgical arts. The result of such quenching is to form .a layer or skin of very hard metal at the quenched surfaces; yet the body of the metal, beneath the very hard layers, retains its original degree of hardness which is substantially softer than that of the external hardened portions.

As a final and desirable step of the inventive process, the hardened outer curved surface portions 23' between grooves 40 are removed; that is, the hardened layers across the cylindrical surfaces 23 of blades 22 are ground away or otherwise taken off. Figs. 6 and 7 illustrate this step of the process. As indicated in Fig. 6, the two previously severed, machined and then surface-hardened portions of the pair of bars 35 are again placed backto-back and are again mounted on the forked spindle 45 which then is rotated. The hardened outer surface portions 23 .are removed from blades 22 simply and uniformly by a grinding member 46, of a suitable abrasive material adapted for metal grinding, thereagainst for a period of time snfficient to remove the hardened layer and sharpen the cutting edges. Subsequently, the finished cutter 12 preferably is wire-brushed to remove any burrs andother extraneous material.

Cutter 12, as produced by the above described process, is distinguished by its unique cutter-blades, each of which comprises a soft metal layer 50 sandwiched between a pair of hard metal layers 51 and 52 (Fig. 7). Viewed another way, grooves 40 are bounded by lateral surfaces 51 and 52 that are hard with respect to portions of the bar intermediate the lateral surfaces. Hard metal layers 51 and 52 are contiguous with the perpendicular surfaces of the cutter blades, whereupon end-surfaces 23 each comprise an intermediate soft metal portion bounded by a pair of very hard cutting surfaces.

In use, the cut whiskers abrading against the soft metal portions of end surfaces 23 effect a self-sharpening hollowing or concaving of the latter. As a result, only the cutting edges at the outer ends of layers 51 and 52 are in contact with comb 20, thereby substantially reducing friction and resultant heat. Intermediate soft layers 50 provide mechanical support for the hard and correspond ha e for adaptation to normal production techniques since all of the apparatus and facilities utilized in carrying out the individual steps of the method are conventional and readily obtainable. Both the unique method of the invention and its novel product are especially distinguished by their simplicity while at the same time the resultant cutter is extremely eflicient and very durable.

While a particular embodiment of the present invention has been described, it is apparent that changes and modifications may be made without departing from the invention in. its broader aspects. The aim of the appended claims, therefore, is to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. An electric shaver cutter comprising a body member and a plurality of parallel cutter elements projecting from and spaced along the length of said body member, each of said cutter elements comprising a soft metal layer integrally sandwiched between a pair of hard metal layers exposed at their outer surfaces and defining oppositely forming cutting edges on said hard metal layers at their remote margins, said soft metal layer being exposed at its edge within the outer dimension of said hard metal layers at their cutting edges and being gradually depressed toward the middle of said soft metal surface to form a concave contour between said cutting edges integral therewith.

2. An electric shaver cutter comprising a body member, a plurality of spaced cutter elements projecting radially away from said member, said cutter elements comprising a layer of hard metal defining a cutting edge and a layer of soft material behind and integral with said Layer of hard metal exposed at the level of the cutting edge to produce areas of differential wear contacting a material to be cut by said cutting edge contiguous with the perpendicular surfaces of said cutter elements.

References Cited in the file of this patent UNITED STATES PATENTS 1,011,938 Gaisman Dec. 19, 1911 1,306,690 Gillespie June 17, 1919 1,630,631 Pauly May 31, 1927 1,813,470 Thompson July 7, 1931 2,160,952 Brenner June 6, 1939 2,168,406 Harris Aug. 8, 1939 2,223,768 Martin Dec. 3, 1940 2,281,250 Ruskin Apr. 28, 1942 2,339,677 Burns Jan. 18, 1944 2,408,790 Mack Oct. 8, 1946 2,467,417 Wurtele Apr. 19, 1949 2,601,720 Carissime July 1, 1952 2,787,829 Bayne Apr. 9,1957

FOREIGN PATENTS 181,527 Austria Mar. 25, 1955 

